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Thread: Need help changing base idle transmission pressures with PCS.

  1. #1
    Junior Member
    Join Date
    Mar 2010
    Posts
    26

    Default Need help changing base idle transmission pressures with PCS.

    It would appear there is no table inside the 4l80E transmission tune to change the base transmission pressure (idle) via the PCS.

    Why is this table not available? I would think there has to be a load vs temp table the PCM is looking up...

    Issue I am having has to do with a transbrake I bought for this trans that uses the internal brake circuit to engage Reverse. Long story short, the spring on this circuit was too weak and the brake activated at 30mph on the road, so I tore it apart and changed the spring out to a heavier spring. Problem now is on cold mornings I can't get the brake to activate (Go in reverse) until the trans warms up. Basicly I need the PCS to command higher line pressures at colder temps.

    Anyone know of a work around for this? I may just have to change the spring to a lighter one, but really wanted a quicker work around!


    Thanks.

  2. #2
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    There is no base pressure table.

    Decrease the Pressure Control Solenoid (Force Motor) Current table.

    Or, turn the calibration screw in/clockwise 1/8 to 1/4 turn on the end of the PCS solenoid.

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